Light emitting device that includes protective film having uniform thickness

ABSTRACT

A light emitting device includes an electrically conductive member provided with a reflective film; a light emitting element mounted on the reflective film; and a protective film continuously covering a surface of the light emitting element and a surface of the reflective film. A thickness of the protective film on the reflective film in a vicinity of the light emitting element is substantially equal to a thickness of the protective film on the reflective film in the region except for the vicinity of the light emitting element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/172,782, filed Feb. 4, 2014, now U.S. Pat. No. 9,087,966 which is adivisional of U.S. patent application Ser. No. 13/217,073, filed Aug.24, 2011, now U.S. Pat. No. 8,679,871, which claims priority to JapanesePatent Application No. 2010-187806, filed Aug. 25, 2010 and JapanesePatent Application No. 2010-203920, filed Sep. 13, 2010, the disclosuresof which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing a lightemitting device having a light emitting element disposed on anelectrically conductive member.

2. Description of Related Art

Attempts have been made in a light emitting device using a lightemitting element as a light source to improve optical output power bydisposing a reflective film containing silver and the like around thelight emitting element, and further to suppress discoloration or thelike of a reflective film by forming a protective film made of aninorganic material by way of sputtering, CVD or the like (see forexample, Patent reference 1: JP 2009-224538A).

Patent reference 1: JP 2009-224538A

However, when a conventional method is used, there has been a problemthat although the optical output power can be improved by the reflectivefilm, decrease in optical output power occurs during the operation. Thatis, in the case of sputtering, CVD, or the like, a material constituenttravels more or less in a straight line toward the object and isdeposited thereon to form a protective film. Therefore, for example, inthe vicinity of a light emitting element, the light emitting elementitself becomes an obstacle and thus a protective film of good qualityhas been unable to be obtained. As a result, deterioration of thereflective film starts to take place from such a portion and whichcauses discoloration of the reflective film.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a lightemitting device capable of maintaining high optical output power whilesuppressing discoloration of the reflective film and a method ofmanufacturing thereof.

A method of manufacturing a light emitting device according to an aspectof the present invention includes, in an order of, an electricallyconductive member preparation step of preparing an electricallyconductive member provided with a reflective film, a light emittingelement disposing step of disposing a light emitting element on thereflective film, and a protective film forming step of forming aprotective film on the reflective film by using an atomic layerdeposition method.

A method of manufacturing a light emitting device according to anotheraspect of the present invention includes, in an order of, anelectrically conductive member preparation step of preparing anelectrically conductive member, a light emitting element disposing stepof disposing a light emitting element on the reflective film, a wiringstep of electrically connecting the electrically conductive member andthe light emitting element by using a wire, a reflective film formingstep of forming a reflective film on each surface of the electricallyconductive member and wire, and a protective film forming step offorming a protective film on the reflective film by using an atomiclayer deposition method.

A light emitting device according to an aspect of the present inventionincludes, an electrically conductive member provided with a reflectivefilm; a light emitting element mounted on the reflective film; and aprotective film continuously covering a surface of the light emittingelement and a surface of the reflective film, wherein a thickness of theprotective film on the reflective film in a vicinity of the lightemitting element is substantially equal to a thickness of the protectivefilm on the reflective film in the region except for the vicinity of thelight emitting element.

According to the present invention, a light emitting device capable ofmaintaining high optical output power while suppressing discoloration ofthe reflective film and a method of manufacturing thereof may beobtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A trough 1F are schematic diagrams for illustrating a method ofmanufacturing a light emitting device according to an embodiment of thepresent invention.

FIG. 2 is a magnified schematic view of the portion encircled withdashed line in FIG. 1F.

FIGS. 3A trough 3G are schematic diagrams for illustrating a method ofmanufacturing a light emitting device according to another embodiment ofthe present invention.

FIG. 4A is a photograph around the connecting portion of the wire andthe reflective film covered with the protective film deposited by usingALD.

FIG. 4B is a photograph around the connecting portion of the wire andthe reflective film covered with the protective film deposited by usinga conventional sputtering method.

FIG. 5A is a magnified section view of an edge portion of the wireconnected to the reflective film in an embodiment of the presentinvention.

FIG. 5B is a photograph corresponding to FIG. 5A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings. The preferred embodimentsare intended as illustrative of a method of manufacturing a lightemitting device to give a concrete form to technical ideas of thepresent invention, and the scope of the invention is not limited tothose described below. Particularly, the sizes, materials, shapes andthe relative positions of the members described in examples are given asan example and not as a limitation to the scope of the invention unlessspecifically stated. The sizes and the positional relationships of themembers in each of the drawings are occasionally shown exaggerated forease of explanation.

First Embodiment

FIGS. 1A through 1F show each step of a method of manufacturing a lightemitting device according to the present embodiment.

FIG. 2 is a magnified schematic view of the portion encircled withdashed line in FIG. 1F.

(Electrically Conductive Member Preparation Step)

First, as shown in FIG. 1A, an electrically conductive member 1 having areflective film 1 b provided on a base member 1 a is prepared(electrically conductive member preparation step). In this embodiment,not only the base member 1 a but also the reflective film 1 b also hasan electric conductivity. In the present embodiment, the electricallyconductive member is constituted with a base member and a reflectivefilm.

The material of the base member 1 a is not specifically limited as longas it has electric conductivity. For the base member 1 a, for example,copper or a copper alloy can be used.

The material of the reflective film 1 b is not specifically limited aslong as it is capable of reflecting light from the light emittingelement 3. For the reflective film 1 b, for example, silver, aluminum orthe like can be used, and particularly, a material containing silver,which has high reflectance is preferably used.

In FIGS. 1B to 1F, the base member 1 a and the reflective film 1 b arenot separately illustrated but are collectively illustrated as theelectrically conductive member 1, for the simplicity of explanation. Theelectrically conductive member may be made solely of a reflective film,or may have another member interposing between the base member 1 a andthe reflective film 1 b. Further, the reflective film 1 b is not neededto be disposed on the entire upper surface of the base member 1 a, aslong as the reflective film 1 b is disposed in the region in thevicinity of the light emitting element 3 (region A in FIG. 2).

(Package Forming Step)

Next, as shown in FIG. 1B, for example, a package 2 having a baseportion 2 a and a side wall 2 b respectively provided on an electricallyconductive member 1 may be formed (package forming step).

The material of the package is not specifically limited and, forexample, a resin or a ceramic may be used. In the case where the packageis made of a resin, an electrically conductive member 1 is arranged in amold for package (not shown) and a resin for the package is introducedinto the mold and is harden, thus, the package 2 and the electricallyconductive member 1 can be integrally formed. A part of the electricallyconductive member 1 is exposed on the bottom surface of a recess definedin the package.

The package 2 is formed integrally with the electrically conductivemember 1, and the material thereof is not specifically limited as longas the material is electrically insulating. As a material of the package2, an electrically insulating material having excellent light resistanceand heat resistance is suitably used, and for example, a thermoplasticresin such as a polyphthalamide, a thermosetting resin such as an epoxyresin, and a glass epoxy and a ceramics can be used. In the presentembodiment, a structure of the package 2 having a side wall 2 b isemployed, but the side wall is not necessarily to be provided.

(Light Emitting Element Disposing Step)

Next, as shown in FIG. 1C, a light emitting element 3 is disposed on thereflective film 1 b (light emitting element disposing step). Morespecifically, the light emitting element 3 can be disposed on thereflective film 1 b with interposing an adhesive member (not shown)therebetween. The adhesive member may either be electrically conductiveor electrically insulating.

The adhesive member is for arranging and fixing the light emittingelement 3 on the electrically conductive member 1 and the materialthereof is not specifically limited. For example, in the case where anelectrically insulating adhesive member is to be used, an epoxy resin ora silicone resin can be employed and in the case where an electricallyconductive adhesive member to be used, an Au—Sn alloy, a SnAgCu alloy, aSnPb alloy, an InSn alloy, Ag, Sn, or Ag can be employed.

For the light emitting element 3, a known light emitting element can beused and, for example, an LED made of a nitride semiconductor(In_(X)Al_(Y)Ga_(1-X-Y)N, 0≦X, 0≦Y, X+Y≦1) capable of emitting bluelight or green light can be used.

(Wiring Step)

Next, as shown in FIG. 1D, the light emitting element 3 and thereflective film 1 b can be electrically connected by using anelectrically conductive wire 4 (wiring step). In this arrangement, thelight emitting element 3 and the base member 1 a are electricallyconnected through the electrically conductive reflective film 1 b.

In the case where the light emitting element 3 has a pair of electrodes(not shown) on the same surface side, and the light emitting element 3is disposed with the side which has the electrodes facing upward(emission observing surface side), a wire 4 is needed to connect witheach electrode as shown in the figure. In this case, if the electricallyconductive member side of the light emitting element 3 has electricallyinsulating property, the adhesive member does not need to beelectrically insulating and an electrically conductive member such as ametal can be used in view of thermal conductivity. In the case where anelectrode is provided on each of the opposite surfaces with respect tothe light emitting element, electric current is supplied to one of theelectrodes through an electrically conductive adhesive member, so thatonly one wire is needed. On the other hand, in the case where the lightemitting element has a pair of electrodes on the same surface side andis disposed with that side down (opposite side from the emissionobserving surface (the opposite side from the electrically conductivemember 1)), the electric current can be supplied to each of theelectrode through the respective electrically conductive adhesivemembers, so that a wire is not needed.

The wire 4 is used for electrically connecting the light emittingelement 3 with the base member 1 a, and the material thereof is notspecifically limited. For the material of the wire 4, for example, amaterial containing at least one of gold, copper, platinum, aluminum,and silver can be used.

(Protective Film Forming Step)

Next, as shown in FIG. 1E, using an atomic layer deposition method(hereinafter may be referred to as “ALD” (Atomic Layer Deposition), aprotective film 5 is deposited and formed on the reflective film 1 b.That is, the protective film 5 is deposited from the emission observingsurface side. Different from a conventional method such as sputtering,ALD is a method for depositing a layer of reaction constituent as asingle-atom layer at each time. The following describes a case where aprotective film of aluminum oxide (Al₂O₃) is deposited and formed usingTMA (trimethyl aluminum) and water (H₂O).

First, TMA gas is introduced to react with the hydroxyl group on thesurface of the reflective film which is the object (first reaction).Next, the excess gas is purged. Thereafter, H₂O gas is introduced toreact with the TMA which is bonded to the hydroxyl group in the firstreaction (second reaction). Next, the excess gas is purged. Then,setting the first reaction, purging, the second reaction, and purging asone cycle, the cycle is repeated to obtain Al₂O₃ with a predeterminedthickness.

Unlike that in the case of sputtering, CVD, or the like, a reactionconstituent travels in a less straight line in ALD. Therefore, thereaction component can be supplied even to a portion in the vicinity ofan obstacle, so that a single molecular layer of the reaction componentcan be deposited at each time, even to a portion in the vicinity of anobstacle. As a result, a protective film of higher quality can bedeposited with more uniform thickness and film quality even to a regionin the vicinity of an obstacle, as well as to other regions free ofobstacles.

Protective film obtained by using ALD has higher quality and higherprotective property compared to that of the protective films obtained byusing a conventional method. Thus, partial discoloration occurs with acertain proportion even in a region free from an obstacle in aprotective film obtained by using a conventional method, however, aprotective film obtained by using ALD exhibits substantially nodiscoloration regardless of the presence of an obstacle. Further, evenwith a small thickness, the protective film obtained by using ADL iscapable of sufficiently protecting the reflective film. Thus, theprotective film can be provided with a smaller thickness than that ofthe protective films obtained by using a conventional method. With thisarrangement, the absorption of light by the protective film can besuppressed and a light emitting device having high optical output powerin its initial properties can be obtained.

In the case where the protective film 5 is formed after disposing thelight emitting element 3, when a conventional method is used, there hasbeen a problem that the light emitting element 3 itself acts as anobstacle, preventing the material constituent of the protective film 5from sufficiently reaching the portions at or near the periphery of thelight emitting element 3. The resulting reduction in quality and/orinsufficient thickness of the protective film 5 has caused deteriorationand discoloration of the reflective film in a region in the vicinity ofthe light emitting element 3 (region A in FIG. 2). This is consideredthat a larger number of pin holes compared with that in the otherportions occur in the deteriorated portions of the protective film,causing sulfurization or bromination of the reflective film which leadsoccurrence of discoloration. The portions in the vicinity of the lightemitting element can produce high optical output power, so that ifdiscoloration of the reflective film in the vicinity of the lightemitting element occurs, the optical output power of the light emittingdevice will be significantly decreased.

Accordingly, with employing ADL, the protective film 5 with excellentfilm quality and the like can be obtained even in the region (region Ain FIG. 2) in the vicinity of the light emitting element. As a result,occurrence of discoloration or the like in the reflective film 1 b ofthe region A can be suppressed. Further, with employing ADL, a thicknessof the protective film 5 on the reflective film 1 b in the vicinity ofthe light emitting element is substantially equal to a thickness of theprotective film 5 on the reflective film 1 b in the region except forthe vicinity of the light emitting element in addition to forming theprotective film 5 with excellent film quality. Therefore, according tothe method of the present invention, the protective film 5 withexcellent film quality can be formed with a thickness required toprevent discoloration of the reflective film 1 b even in the vicinity ofthe light emitting element that would be an obstacle when forming theprotective film 5, which makes it possible to effectively preventdeterioration of the reflective film 1 b.

Particularly, in the case where the adhesive member presents within thecircumference of the light emitting element and without reaching a sidesurface of the light emitting element when seen in a cross-sectionalview, a gap may be created between the circumference of the bottomsurface of the light emitting element and the reflective film. Even insuch a case, with using ALD, the protective film can be formed also onthe reflective film in the gap.

In the case where the protective film is to be formed using aconventional method after the wiring step, there has been a problem thatthe existence of wire 4 (the wire 4 acts as an obstacle) prevents thematerial constituent of the protective film 5 from sufficiently reachingthe reflective film 1 b beneath the wire 4. The resulting reduction inquality and/or insufficient thickness of the protective film 5 hascaused discoloration of the reflective film 1 b in the portion.Particularly, among the regions beneath the wire 4, there has been aproblem in the region in the vicinity of the connecting portion of thewire 4 and the reflective film 1 b (region B in FIG. 2) that when aconventional method is used, not only discoloration of the reflectivefilm 1 a but also corrosion of the reflective film 1 b takes place andresults in breaking of the wire 4.

However, with a use of ADL, the protective film 5 with excellent filmquality and the like can be formed even in the region (region B in FIG.2) directly under the wire 4. Accordingly, deterioration of theprotective film in the region B can be reduced and not onlydiscoloration but also braking of the wire can be suppressed.

In addition, according to the method of manufacturing in which theprotective film 5 is formed by means of ALD, the protective film 5 isformed so as to fill a gap formed between an edge portion of the wire 4connected to the reflective film 1 b and the reflective film 1 b,thereby preventing discoloration and corrosion of the reflective film 1b positioned around the gap.

In addition, according to the present invention, in spite of a form ofthe wire 4, for example, a shape of the edge portion of the wire 4 and adirection of the wire 4 extending from the edge portion etc., theprotective film 5 is formed on the reflective film 1 b around the edgeportion of the wire 4 with a substantially equal thickness.

Further, according to the present invention, a thickness of theprotective film 5 on the reflective film 1 b in the vicinity of the edgeportion of the wire 4 is substantially equal to a thickness of theprotective film 5 on the reflective film 1 b in the region except forthe vicinity of the edge portion of the wire 4. Therefore, discolorationand corrosion of the reflective film 1 b around the edge portion of thewire 4 can be effectively prevented.

FIGS. 4A and 4B each shows the image around the connecting portion ofthe wire and the reflective film, taken from the emission observingsurface side after the protective film depositing step. FIG. 4A shows aprotective film made of Al₂O₃ with a thickness of 30 nm, deposited byusing ALD, and FIG. 4B shows a protective film made of Al₂O₃ with athickness of 30 nm, deposited by using a conventional sputtering method.These images were taken after the reflective films made of Ag were leftin a condition of excess sulfide for a given period time to facilitatesulfurization of the films (both were tested under the same condition).As shown in FIG. 4A, even exposed under an easily-sulfurized condition,the protective film formed by using ALD showed no discoloration not onlyin the regions away from the wire and free of obstacles but also in theregion (corresponding to region B in FIG. 2) directly under the wire. Onthe other hand, as shown in FIG. 4B, the protective film deposited bysputtering showed dot shaped discoloration at a number of positions evenin the regions away from the wire and free of obstacles, and showedcontinuous discoloration in the regions around the connecting portion ofthe wire and the reflective film, including the region directly underthe wire (this is considered that microscopic unevenness exists in theconnecting portion of the wire and the reflective film and acts as anobstacle, so that discoloration occurred not only in the region directlyunder the wire but also in the entire region around the connectingportion). The results of the experiments described above exhibit thatforming the protective film with a use of ALD enables to obtain aprotective film of excellent quality.

In order to improve the optical output power of the light emittingdevice, for example, a wire made of a material containing silver whichhas high reflectance can be employed to obtain efficient lightreflection from the wire. However, as in the case of discoloration ofreflective film, discoloration of the wire which is made of asilver-containing material may also present a problem. Even in such acase, with a use of ALD, the protective film can be formed on the entiresurface of the wire including the emission observing surface side of thewire to the opposite side (reflective film side) of the wire, with thereason as described above. Thus, discoloration or the like of the wirecan be suppressed efficiently.

In the case where the protective film is formed with a use of aconventional method after the package forming step, there has been aproblem that due to the existence of the side wall of the package 2 (theside wall of the package acts as an obstacle), the material constituentof the protective film 5 cannot sufficiently reach a portion of thebottom surface defining the recess in the vicinity of the side wall(region C in FIG. 2). The resulting reduction in quality and/orinsufficient thickness of the protective film 5 caused discoloration ofcorresponding part of the reflective film 1 b. Discoloration of theprotective film 1 b in the vicinity of the side wall of the package 2may not pose harmful effect on the optical output power as that of thediscoloration of the reflective film 1 b in the region A, but theproblem can never be ignored.

Accordingly, with employing ADL, the protective film 5 which isexcellent in film quality and the like can be obtained even in theregion (region C in FIG. 2) in the vicinity of the side wall 2 b. Withthis arrangement, occurrence of discoloration of the protective film 1 bin the region C can be suppressed and decrease in the optical outputpower of the light emitting device can be further reduced.

In the case where the protective film 1 b contains silver, there hasbeen a problem that although having high reflectance is an advantageousproperty, with a use of a conventional method, the optical output powertends to decrease due to discoloration of the reflective film 1 b in thecourse of time. However, the protective film formed by using ALD iscapable of efficiently suppressing occurrence of discoloration or thelike, even in a case where the protective film is made of asilver-containing material, and thus is preferable.

For the protective film 5, for example, aluminum oxide (Al₂O₃), silicondioxide (SiO₂), aluminum nitride (AlN), or silicon nitride (Si₃N₄) canbe employed, and preferably, aluminum oxide or silicone dioxide, morepreferably aluminum oxide can be used. With this arrangement, absorptionof light from the light emitting element can be suppressed and aprotective film of excellent protection property can be obtained.

The thickness of the protective film 5 can be 1 nm or greater and lessthan 50 nm, preferably 2 nm or greater and less than 25 nm, morepreferably 3 nm or greater and less than 10 nm. With this arrangement,while maintaining the functions as a protective film, absorption oflight from the light emitting element by the protective film can besuppressed, so that the light emitting element of high optical outputpower can be obtained.

As shown in the figures such as FIG. 1E, the protective film 5 is formednot only on the bottom surface defining the recess of the package 2 butalso on the upper surface and inner wall of the side wall 2 b, but forexample, the upper surface and inner wall of the side wall 2 b can bearranged so that the protective film 5 is not formed thereon. A regionwhich is free of the protective film 5 can be provided in a part of thebottom surface defining the recess of the package 2.

(Other Steps)

As shown in FIG. 1F, if required, a sealing member 6 can be formed inthe recess defined by the side wall 2 b of the package (sealing memberforming step). Then, after cutting the electrically conductive member 1so as to obtain each light emitting device capable of functioningindividually (electrically conductive member cutting step), if required,each electrically conductive member 1 is bent to the back side of thecorresponding package 2 (electrically conductive member bending step),to form individual light emitting devices.

The sealing member 6 is to enclose the light emitting element 3, and thematerial thereof is not specifically limited as long as it allows thelight from the light emitting element 3 to pass through to the outside.For the material of the sealing member 6, for example, a silicone resin,an epoxy resin, or the like can be used. Further, a fluorescentsubstance capable of emitting light upon receiving the light from thelight emitting element 3 can be included also in the sealing member 6.For the fluorescent substance, a known substance can be used, and in thecase where the light emitting element 3 emits blue light, a yellow lightemitting fluorescent substance such as a YAG-based fluorescentsubstance, a TAG-based fluorescent substance, and a strontiumsilicate-based fluorescent substance can be used to obtain white lightemission from the light emitting device.

Second Embodiment

The present embodiment will be described below with reference to FIGS.3A to 3G. In this embodiment, like members as in the first embodimentare designated by like numerals and their repeated description will beomitted.

(Electrically Conductive Member Preparation Step)

First, as shown in FIG. 3A, the electrically conductive member 1 isprepared (electrically conductive member preparation step). In thepresent embodiment, different from that in the first embodiment, theelectrically conductive member is made of the base member alone, and thereflective film 1 b is not provided in this step.

(Package Forming Step)

Next, as shown in FIG. 3B, a package 2 having a base portion 2 a and aside wall 2 b provided on an electrically conductive member 1 can beformed (Package Forming Step).

(Light Emitting Element Disposing Step)

Next, as shown in FIG. 3C, a light emitting element 3 is disposed on theelectrically conductive member 1 (light emitting element disposingstep). More specifically, the light emitting element 3 can be disposedon the electrically conductive member 1 using an adhesive member (notshown).

(Wiring Step)

Next, as shown in FIG. 3D, the electrically conductive member 1 and thelight emitting element 3 are electrically connected by using anelectrically conductive wire 4 (wiring step).

(Reflective Film Forming Step)

Next, the reflective film 1 b is formed on the surface of theelectrically conductive member 1 and the wire 4 (reflective film formingstep). For the sake of drawing the figure, the reflective film 1 b onthe surface of each wire 4 is not shown in FIG. 3E, but according to thepresent embodiment, the reflective film 1 b is actually formed not onlyon the surface of each electrically conductive member 1 but also on thesurface of each wire 4. The reflective film 1 b also covers theconnecting portion of the electrically conductive member 1 and the wire4.

With this arrangement, absorption of light by the surface of the wires 4can be suppressed and a light emitting device of further higher opticaloutput power can be obtained.

For the method of forming the reflective film 1 b, a known method can beemployed. Particularly, with a use of an electroplating method, thereflective film 1 b can be formed selectively on the surfaces of theelectrically conductive member 1, the wire 4, or the like, withoutforming the reflective film (metal film) on the surface of the lightemitting element 3 which is not electrically conductive. For thematerial of the reflective film 1 b, the same materials as in the firstembodiment can be used, and silver or the like can be employed.

(Protective Film Depositing Step)

Next, as shown in FIG. 3F, the protective film 5 is formed on thesurface of the reflective film 1 b by using ALD. For the sake of drawingthe figure, the protective film 5 on the surface of each wire 4 is notshown in FIG. 3F, but in the present embodiment, actually, theprotective film 5 is formed also on the surface of each wire 4 over thereflective film 1 b.

(Other Steps)

As shown in FIG. 3G, if required, a sealing member 6 can be formed inthe recess defined by the side wall 2 b of the package (sealing memberforming step). Then, after cutting the electrically conductive member 1so as to obtain each light emitting device capable of functioningindividually (electrically conductive member cutting step), if required,each electrically conductive member 1 is bent to the back side of thecorresponding package 2 (electrically conductive member bending step),to form individual light emitting devices.

INDUSTRIAL APPLICABILITY

The method of manufacturing the light emitting device according to thepresent invention can be applied to manufacturing various kinds of lightemitting devices such as illumination light sources, light sources forvarious kinds of indicators, light sources for automobile use, lightsources for displays, back light sources for liquid crystal displays,light sources for sensors, signals, and so on.

It is to be understood that although the present invention has beendescribed with regard to preferred embodiments thereof, various otherembodiments and variants may occur to those skilled in the art, whichare within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

This application is based on applications No. 2010-187806 filed in Japanon Aug. 25, 2010, and No. 2010-203920 filed in Japan on Sep. 13, 2010,the contents of which are incorporated hereinto by references.

The invention claimed is:
 1. A light-emitting device comprising: asubstrate that includes a pair of electrically conductive members and abase portion; a light emitting element mounted on the substrate, whereina gap is located between a portion of the substrate and a portion of thelight emitting element, a protective film having a portion that covers asurface of the light emitting element, and a portion that is disposed onthe substrate in the gap between said portion of the substrate and saidportion of the light emitting element, and wherein a thickness of theprotective film in said portion that covers the surface of the lightemitting element is substantially equal to a thickness of the protectivefilm in said portion that is disposed on the substrate in the gapbetween said portion of the substrate and said portion of the lightemitting element.
 2. The light-emitting device of claim 1, wherein thelight emitting element includes a pair of electrodes that are bothlocated on a substrate side of the light emitting element.
 3. Thelight-emitting device of claim 1, wherein the light emitting element ismounted on the substrate via a plurality of adhesive members.
 4. Thelight-emitting device of claim 3, wherein the adhesive members areelectrically conductive.
 5. The light-emitting device of claim 4,wherein each of the adhesive members comprises one or more of an Au—Snalloy, a SnAgCu alloy, a SnPb alloy, an InSn alloy, Ag, Sn, and Ag. 6.The light-emitting device of claim 4, wherein the light emitting elementcomprises a nitride semiconductor.
 7. The light-emitting device of claim4, wherein the protective film comprises aluminum oxide.
 8. Thelight-emitting device of claim 4, wherein the protective film comprisessilicon dioxide.
 9. The light-emitting device of claim 4, wherein thesubstrate comprises a base portion comprising a ceramic material. 10.The light-emitting device of claim 4, further comprising a side walldisposed above the electrically conductive members.
 11. Thelight-emitting device of claim 4, wherein the protective film is a filmdeposited via atomic layer deposition.
 12. The light-emitting device ofclaim 4, wherein a thickness of the protective film is 1 nm or greaterand less than 50 nm.
 13. The light-emitting device of claim 4, wherein athickness of the protective film is 2 nm or greater and less than 25 nm.14. The light-emitting device of claim 4, wherein a thickness of theprotective film is 3 nm or greater and less than 10 nm.
 15. Thelight-emitting device of claim 1, wherein the light emitting elementcomprises a nitride semiconductor.
 16. The light-emitting device ofclaim 1, wherein the protective film comprises aluminum oxide.
 17. Thelight-emitting device of claim 1, wherein the protective film comprisessilicon dioxide.
 18. The light-emitting device of claim 1, wherein theprotective film is a film deposited via atomic layer deposition.
 19. Thelight-emitting device of claim 1, wherein a thickness of the protectivefilm is 1 nm or greater and less than 50 nm.
 20. The light-emittingdevice of claim 1, wherein a thickness of the protective film is 2 nm orgreater and less than 25 nm.
 21. The light-emitting device of claim 1,wherein a thickness of the protective film is 3 nm or greater and lessthan 10 nm.